Adaptive anti-scatter device

ABSTRACT

An adaptive X-ray anti-scatter device (20) for placement in the source-detector axis (22) of an X-ray imager (8) comprising:—an anti-scatter filter having a source orientable surface and a detector orientable surface, wherein the anti-scatter filter comprises a plurality of realignable slats (24) for absorbing incident X-rays, wherein the slats are separated by a plurality of interstitial portions (26); and—a first actively deformable member (26a) comprising a first set of one or more actively deformable actuators (28a, 28b) disposed across a first region of the first actively deformable member (26a), wherein one or more actively deformable actuators of the first set of one or more actively deformable actuators are configured to change the alignment of a corresponding of slat of the anti-scatter filter in relation to the source-detector axis, wherein at least a portion of each actuator of the first set of one or more actively deformable actuators is partially or fully recessed within the interstitial portions of the anti-scatter filter, and at least one actuator of the first set of one or more actively deformable actuators is in contact with at least one realignable slat of the plurality of slats, so that a deformation of the at least one actuator of the first set of one or more actively deformable actuators of the one or more actively deformable actuators causes a corresponding change to the alignment of the at least one corresponding slat from a first alignment to a second alignment relative to the source-detector axis.

FIELD OF THE INVENTION

This application relates to an adaptive X-ray anti-scatter device forplacement in the source-detector axis of an X-ray imager, an X-raydetector, an X-ray imaging system, a method for manufacturing anadaptive anti-scatter device, a computer program element comprisinginstructions for the operation of a 3D or 4D printer, and a computerreadable medium comprising instructions for the operation of a 3D or 4Dprinter.

BACKGROUND OF THE INVENTION

To resolve structures in an X-Ray image of a region of interest of apatient, it is important that the X-Ray radiation incident on a givenportion of an X-Ray detector has travelled in a straight line between anX-Ray source and the given portion of the X-Ray detector. However, thepassage of X-rays through different types of tissue in a patient causesscattering of the X-Ray beam. This scattering can degrade the quality ofa received X-Ray image. Accordingly, anti-scatter grids are provided inX-Ray imaging systems to reduce or to eliminate scattered X-Rayradiation.

WO 2018/037128 A1 discusses a variable focus X-Ray anti-scatter device,although such equipment may be further developed.

SUMMARY OF THE INVENTION

The object of the present invention is solved by the subject-matter ofthe independent claims. Further exemplary embodiments are evident fromthe dependent claims in the following description.

Therefore, according to a first aspect of the invention, there isprovided an adaptive anti-scatter device for placement in thesource-detector axis of an X-ray imager. The adaptive anti-scatterdevice comprises:

-   -   an anti-scatter filter having a source orientable surface and a        detector orientable surface. The anti-scatter filter comprises a        plurality of realignable slats for absorbing incident X-rays.        The slats are separated by a plurality of interstitial portions.        The adaptive anti-scatter device also comprises:        -   a first actively deformable member comprising a first set of            one or more actively deformable actuators disposed across a            first region of the first actively deformable member.

At least a portion of the first set of one or more actively deformableactuators of the first set of actively deformable actuators is partiallyor fully recessed within the interstitial portions of the anti-scatterfilter. Further, at least one actuator of the first set is configured tochange the alignment of a corresponding slat of the anti-scatter filterin relation to the source-detector axis. More in particular, theactuator may be in contact with at least one realignable slat of theplurality of slats, so that a deformation of the actuator causes thecorresponding change to the alignment of the corresponding slat, forexample from a first alignment to a second alignment relative to thesource-detector axis.

Accordingly, it is possible to vary an angulation of slats in anadaptive anti-scatter device as a function of the source-image distance.This ensures that for each setting of the source-image distance in anX-Ray imager, scattered X-Rays are blocked from impinging oninappropriate sections of an X-Ray detector. Therefore, the adaptiveanti-scatter filter enables the provision of high-quality X-Ray imagesfrom a wide range of source image distances. Furthermore, the structureof the adaptive anti-scatter device according to the first aspect issuitable for manufacturing using a 3D or 4D printing process, enablingcost and efficiency savings when manufacturing the adaptive anti-scatterdevice. Because at least a portion of each actuator of one or more ofthe first set of one or more actively deformable actuators is partiallyor fully recessed within the interstitial portions, the X-Rayanti-scatter filter is compact, and simpler to manufacture.

Optionally, the adaptive anti-scatter device further comprises a coverelement that is translucent to X-rays arranged to cover at least oneside of the adaptive anti-scatter device. The slats of the anti-scatterfilter are coupled to the cover element.

Accordingly, the realignable (tiltable) slats of the anti-scatter filtermay be protected from one, or both sides from mechanical damage or theingress of dust or foreign objects, for example.

Optionally, the lateral spatial density of actively deformable actuatorsof the first actively deformable member varies as a function of thelateral location on the first actively deformable member.

Accordingly, a greater proportion of X-rays directly in line with theX-Ray source can be directed to a geometrically appropriate portion ofan X-Ray detector, and a greater proportion of scattered X-rays are berejected.

Optionally, the first actively deformable member further comprises asecond set of one or more actively deformable actuators disposed in asecond region of the first actively deformable member. The first regionis laterally closer to the source-detector axis than the second region.The second region of the first actively deformable member comprises agreater spatial density of actively deformable actuators than the firstregion.

Accordingly, because the second region of the first actively deformablemember has a greater spatial density of actively deformable actuators,the second region will deform to a greater extent than the first regionupon the application of a driving signal. Because the second region islocated laterally further away from the source-detector axis compared tothe first region, the realignable (tiltable) slats (lamellae) may bealtered appropriately to reject scattered X-rays effectively for everylateral location of the X-Ray detector.

Optionally, the anti-scatter device further comprises a second activelydeformable member comprising a third set of one or more activelydeformable actuators configured to change the alignment of acorresponding slat of the anti-scatter filter in relation to thesource-detector axis. Each actively deformable actuator of the third setof one or more actively deformable actuators is formed within theinterstitial portions of the anti-scatter filter and in contact with atleast one corresponding slat of the plurality of slats, so that adeformation of one or more of the third set of one or more activelydeformable actuators causes a corresponding change to the alignment ofthe at least one corresponding slat relative to the source-detectoraxis.

Accordingly, a further layer of deformable actuators may be providedhaving a different deformation ratio compared to the initial layer ofdeformable actuators.

Optionally, the second actively deformable member is located closer tothe source-orientable face than the first actively deformable member.The lateral spatial density of actively deformable actuators of thesecond actively deformable member is greater than the lateral spatialdensity of the actively deformable actuators of the first activelydeformable member at corresponding lateral positions of the first andsecond deformable members.

Accordingly, the portions of slats (lamellae) that are closer to thesource may be moved (tilted) a greater distance compared to portions ofslats that are further from the source.

Optionally, the interstitial spaces of the anti-scatter filter compriseactuators of the first and/or second actively deformable member, whereineach interstitial space comprises a first set of one or more activelydeformable actuators, and a second plurality of non-deformableactuators, or actuators that are less deformable than the actuators inthe first set of one or more actively deformable actuators.

Accordingly, the expansion ratio inside the interstitial spaces can becarefully controlled by providing a greater or smaller proportion ofactively deformable actuators compared to non-deformable (orless-deformable) actuators.

Optionally, the actuators of the first and/or second actively deformablemember are controllable with a unified control signal, or the actuatorsof the first and/or second actively deformable member are divided intoindividually addressable actuator regions.

Accordingly, the actuators of the first and/or second activelydeformable member may be driven by a control signal that is at leastpartially a function of the source-detector distance of an X-Ray imagingsystem using the adaptive anti-scatter filter. In the case of a controlsignal enabling the individual addressing of actuator regions, a finecontrol of the slat (lamellae) tilt ratio is possible. In the case thata unified control signal is used to actuate every actuator regionsimultaneously, a low-cost (simpler) signal control approach ispossible.

Optionally, at least one of the first, second, and/or third pluralitiesof actively deformable actuators comprise actively deformable actuatorsof an electro-active or thermally-active polymer or metal alloy.

Accordingly, the actuators may be produced using materials that arecompatible with 3D or 4D printing techniques.

Optionally, the actively deformable actuators are configured to shrinkin the plane parallel to the lateral face of the adaptive anti-scatterdevice under the influence of an actuating signal.

Optionally, the actively deformable actuators are configured to expandin the plane parallel to the lateral face of the adaptive anti-scatterdevice under the influence of an actuating signal.

Optionally, the set of one or more actively deformable actuators of thefirst actively deformable member comprises one or more activelydeformable actuators configured to shrink in the plane parallel to thelateral face of the adaptive anti-scatter device, and a one or moreactively deformable actuators configured to expand in the plane parallelto the lateral face of the adaptive anti-scatter device, under theinfluence of an actuating signal.

Accordingly, fine control of the placement of respective actuator groupsthat can expand or contract enables the fine-tuning of the deflectionpattern of the adaptive anti-scatter filter and the provision of morecomplicated deflection patterns.

According to a second aspect, there is provided an X-ray detectorassembly comprising:

-   -   an X-ray detector, and    -   at least one anti-scatter device according to the first aspect        or its embodiments.

Accordingly, such an X-Ray detector assembly can adaptively change itsscatter rejection characteristic based at least partially on the sourceto distance ratio of a system that the X-Ray detector assembly is usedinside.

According to a third aspect, there is provided an X-ray imaging systemhaving a variable source-imaging distance comprising:

-   -   an X-ray source configured to emit a beam of X-ray radiation        directed towards a patient imaging area of the X-ray imaging        system along a source-detector axis;    -   an X-ray detector assembly according to the second aspect        configured to detect X-ray radiation emitted from the X-ray        source; and    -   a controller configured to provide a control signal to the first        actively deformable member of the anti-scatter device of the        X-ray detector.

The X-ray source and/or the X-ray detector are configurable so that theycan be separated by at least a first and a second different sourcedetector distance.

The controller is configured to monitor the source detector distance ofthe X-ray source and X-ray detector, and to generate a control signalfor the first actively deformable member, to set the first activelydeformable member using the control signal, and to obtain X-ray imagingdata from the X-ray detector with the first actively deformable memberconfigured at an appropriate alignment for the source detector distanceof the X-ray source and X-ray detector.

Accordingly, an X-Ray imaging system according to the third aspect iscapable of providing images with significant scatter reduction eventhough the source to detector distance is variable.

According to a fourth aspect, there is provided a method formanufacturing an adaptive anti-scatter device comprising:

-   -   a) providing an anti-scatter filter having a source orientable        surface and a detector orientable surface, wherein the        anti-scatter filter comprises a plurality of realignable slats        for absorbing incident X-rays, wherein the realignable slats are        separated by a plurality of interstitial portions; and    -   b) providing a first actively deformable member comprising a        first set of one or more actively deformable actuators disposed        across a first region of the first actively deformable member.        This step further includes:

providing at least a portion of the first set of one or more activelydeformable actuators within the interstitial portions of theanti-scatter filter in a partially or fully recessed manner, andcontacting at least one actuator of the first set of one or moreactively deformable actuators with at least one realignable slat of theplurality of slats such that a deformation of the at least one actuatorcauses a change of the alignment of the corresponding slat in relationto the source-detector axis.

Accordingly, an adaptive anti-scatter device having integral actuationcan be manufactured, leading to a more compact and easy to produceadaptive anti-scatter device.

Optionally, either or both of a) and/or b) are performed using a 3D or a4D printer. In other words, either or both providing steps may compriseadditive manufacturing by means of a 3D or 4D printer.

Accordingly, the adaptive anti-scatter device may be producedsubstantially automatically, for example being controlled through a setof suitable instructions for operation of such printer.

Optionally, the anti-scatter filter is an anti-scatter grid.

According to a fifth aspect, there is provided a computer programelement comprising instructions for the operation of a 3D or 4D printerwhich, when addressed to a 3D or 4D printer, cause the 3D or 4D printerto follow the method of the fourth aspect.

According to a sixth aspect, there is provided a computer readablemedium comprising instructions for the operation of a 3D or 4D printerof the fifth aspect.

In this application, the term “adaptive anti-scatter device” means ananti-scatter filter for use in an X-Ray imaging system havingrealignable slats (lamellae). Realignment of the slats enables adaptivespatial filtering of X-Ray scatter, which varies as the source todetector distance is adjusted. Most preferably this adaptation occurs asat least a partial function of the source to detector separationdistance of an X-Ray imaging system. The most common form of ananti-scatter device is a rectangular or square grid of X-Ray opaquematerial comprising slats that are angled with respect to the source todetector direction. However, filtering performance may also arise usingan anti-scatter device having a single dimension of angled slats (in themanner of a comb) which can benefit from the technique discussed herein,and thus the provision of an anti-scatter filter in a grid form is notessential.

In this application, the term “realignable slat” refers to a tiltablelamella, that when built up into a filter can filter scattered X-rays.Accordingly, the realignable slats may be provided as lamellae of leador molybdenum, for example. The fact that the slats are “realignable”means that there are each configurable into a range of angles withrespect to a lateral (x-y) plane of the adaptive anti-scatter device.This realignment may, for example, be enabled by gluing a strip ofresilient polymer to a lead or molybdenum wafer strip, to enable theslat (lamella) to reorient with respect to the source detector axis.

Optionally, the slats are realignable between being perpendicular to thelateral plane to being aligned so as to form an enclosed angle betweenthe realignable slat and the lateral plane of the anti-scatter device inthe ranges: 90 degrees to 85 degrees, 90 degrees to 80 degrees, 90degrees to 75 degrees, 90 degrees to 70 degrees, 90 degrees to 65degrees, 90 degrees to 60 degrees. It is not required that all slats aresimultaneously at the same alignment. For example, at a specific sourceto detector distance, the relative angulation of each slat to itspredecessor may increment by a certain amount as a given position on thelateral plane of the adaptive anti-scatter filter moves away from asource to detector axis to account for X-ray optics.

In this application, the term “interstitial portion” refers to theregion in between neighboring realignment slats (lamellae). Optionally,the interstitial portion is empty (comprises air), or interstitialportion may comprise a compressible filler material such as paper, foam,rubber, or the like. The filling of the interstitial portions may varyover different lateral portions of the adaptive anti-scatter device.

In this application, the term “actively deformable member” comprises aportion of material that upon the application of a driving signal canchange its shape by expanding, or contracting, and transmit a force toan abutting item whilst doing so. The “actively deformable member” isdisposed at least partially in the interstitial portions of theanti-scatter filter, although in some embodiments an actively deformablemember may be entirely comprised inside the interstitial portions. Theactively deformable member is capable of changing the orientation of aplurality of slats of an anti-scatter filter, and thus typically is asheet-like member capable of insertion or partial insertion into theinterstitial portions of an anti-scatter filter. In one option, theactively deformable member comprises a layer of actively deformablematerial having one side with upstanding linear vanes corresponding tointerstitial portions of an anti-scatter grid. The vanes are pushed intotheir respective interstitial spaces so as to abut the realignableslats. The actively deformable member may also be an internal layer thatis 3D printed into the interstitial portions.

At least a portion of the actively deformable member is in contact withthe anti-scatter filter, such that when the actively deformable memberexpands or contracts, a realignment in the anti-scatter filter isaffected.

Optionally, the actively deformable member may be comprised of anactuator material that expands or contracts in the presence of thermalenergy. Optionally, the actively deformable member may be comprised ofan actuator material that expands or contracts under the application ofan electrical field, a potential difference, or a magnetic field.Optionally, the actively deformable member may be a microfluidic elementsuch as a microfluidic bladder, optionally fabricated from rubber orsilicone, that expands and contracts as gas or fluid is pumped into orout of the bladders, respectively. Optionally, the actively deformablemember may be an auxetic structure wherein a small mechanical actuationcauses a much larger affirmation response. Optionally, the activelydeformable member may be comprised of any combination of the abovetechniques. Optionally, the actively deformable member is anelectroactive polymer, preferably comprising a monomer selected from thegroup consisting of vinylidene fluoride and trifluorovinyl. Optionally,the actively deformable member is a shape-memory alloy such ascopper-aluminium-nickel, or nickel-titanium alloy. Thus, the activelydeformable member can be configured to move from an initial expandedposition to a contracted position, or to begin from an initialcontracted position and expand (deformation is considered in thefollowing application has meaning shrinking or expanding, as the contextrequires).

In the following application, the term “actively deformable actuator”defines the simplest unit of space of an “actively deformable member”capable of affecting a change of shape of the actively deformablemember. In other words, several actively deformable actuators may beassembled into the interstitial space, with at least one activelydeformable actuator in contact with a realignable slat (lamella). Ofcourse, the deformable actuators will themselves change in volume asthey undergo deformation. Optionally, the actuators are substantiallycubic, although the application is not so limited and substantially anyshape producible using, for example, a 3D or 4D printer may be applied.Alternatively, the term “actively deformable actuator” may beinterpreted as an “actively deformable voxel”, meaning a portion of 3Dspace that can change shape, and exert a force against a realignment orslat upon the application of the driving signal. Optionally, theactively deformable actuator may comprise an auxetic cell.

The activation of a thermal actuator material can be performed usingdifferent temperature levels. A temperature difference may be used toswitch the actuator between a first and a second position (or even arange of positions in-between). In this option, a thermal actuatormaterial used in the actuator of an adaptive anti-scatter grid could begenerated by local heating elements which could be part of the carrierelement as homogenous heating foils, heating wires, and/or local heatingelements which could be printed by conductive material and connected toa central programmable power supply (or via matrix controller havingindividually addressable sub-segments).

Optionally, the actuator material could comprise pre-deformed metalfoils in the manner of the spring, alternatively the use of bi-metalsprings.

In the following application, the term “lateral spatial density” refers,for example, to the ratio between an area of an actively deformablemember of actuators versus a passive area over a given layer of theadaptive anti-scatter filter. For example, a layer comprising anactively deformable layer axially closer to the X-ray detector in usemay optionally have a higher lateral spatial density of activelydeformable actuators compared to an actively deformable layer axiallyfurther away from to the X-ray detector in use, enabling the ends of theslats closer to the X-Ray detector to have their divergence adjusted toa greater degree compared to the ends of the slats closer to the X-Raysource.

In the following application, the term “partially or fully recessed”refers to the alignment of an actively deformable member relative to theslats of the anti-scatter device. A given portion of the activelydeformable member must be able to transfer a substantially transverseforce (relative to the source to detector axis) to the realignable slatsof anti-scatter device. Typically at least one actively deformableactuator of the actively deformable member abuts a realignable slat,enabling direct transfer of the transverse force to the realignableslat. However it is also foreseeable that a portion of inert materialcould transfer the transverse force to the realignable slat from anactively deformable actuator. Because a portion of the activelydeformable member abuts one or more realignable slats, the activelydeformable actuator should, in one option, be placed as a layer entirelywithin the interstitial portions of the anti-scatter filter. Optionally,an actively deformable member can be located across the sourceorientable surface and/or across the detector orientable surface, withextensions abutting the one or more realignable slats at least partiallyextending into the interstitial portions. For example, the extensionsmay extend into the interstitial portion by 5%, 10%, 15%, or 20% or thetotal depth of the slat height (substantially in the direction of thesource-detector axis).

In the following application, the term “3D printer” refers to a machinefor additively manufacturing parts using the sequential deposition oflayers of material according to a computer program, or list of computerinstructions. Different types of materials (such as plastics and metals)may be deposited in intricate and complicated patterns, allowing themanufacture of an adaptive anti-scatter filter as described herein.

In the following application, the term “4D printer” refers to a machinefor additively manufacturing parts using the sequential deposition oflayers of material according to a computer program, or list of computerinstructions. Different types of materials (such as plastics and metals)may be deposited in intricate and complicated patterns, allowing themanufacture of an adaptive anti-scatter filter as described herein.However, such a printer is capable of generating complicated shapes thatare able to change their physical form in response to one or more of athermal, mechanical, electrical stimulus for example. An auxetic elementis one example of the output of such a 4D printer.

Accordingly, a basic idea to be discussed further in the application isthat an adaptive anti-scatter filter (grid) having, for example, amixture of inactive and active voxels (actuators) that cause the gridmembers to change their angulation upon the application of an externalsignal at least partially related to the source detector separation ofan X-Ray imaging system. This enables the focal distance of theanti-scatter grid to be made equal to the source to image distance atevery source to image distance setting, enabling the image qualityobtained from an X-Ray detector using the adaptive anti-scatter grid tobe improved because less primary radiation is absorbed due to defocus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a side-view of a conventionalanti-scatter grid.

FIG. 2 schematically illustrates a C-arm X-Ray imaging system accordingto an example of the third aspect.

FIG. 3a ) schematically illustrates a front view of an exemplaryanti-scatter grid according to the first aspect.

FIG. 3b ) schematically illustrates an enlarged view of the front of anexemplary anti-scatter grid according to the first aspect.

FIG. 3c ) schematically illustrates a front view of an exemplary 2Dembodiment of the anti-scatter grid according to the first aspect.

FIG. 4a ) schematically illustrates a side view of an exemplaryanti-scatter grid according to the first aspect in a firstconfiguration.

FIG. 4b ) schematically illustrates a side view of an exemplaryanti-scatter grid according to the first aspect in a secondconfiguration.

FIG. 5 schematically illustrates a side view of a further exemplaryanti-scatter grid according to the first aspect superimposed into twoseparate configurations.

FIG. 6 schematically illustrates a front view of a further exemplaryanti-scatter grid comprising a varying lateral spatial density of activeactuators.

FIG. 7 schematically illustrates a front view of a further exemplaryanti-scatter grid comprising a control signal arrangement.

FIGS. 8a ) to c) schematically illustrate a deformable auxeticcontraction cell in various degrees of contraction.

FIG. 9 schematically illustrates a method according to the fourthaspect.

DETAILED DESCRIPTION OF EMBODIMENTS

Many X-Ray systems have a variable source to image distance (SID).Examples of such systems are, for example, A C-arm system (as depictedin FIG. 1), or other types of digital X-Ray imagers (such as mammographyscanners) with adjustable distances between the source and detector.Such systems typically comprise an anti-scatter grid having slats(lamellae) at a fixed orientation. This orientation is chosen, forexample, to exclude an optimum amount of scatter at a specific source toimage distance of the X-Ray imager (for example, the statistically mostcommonly used soft image distance).

FIG. 1 illustrates an exaggerated example of how grid slats (lamellae)should be ideally focused as the SIG changes. In FIG. 1, a schematicside view of a fixed anti-scatter grid 20 is shown. The array of lines23 b illustrate the optimal alignment of the slats (lamellae) for sourceimage distance SID₁. The array of lines 23 a illustrate the optimalalignment of the slats (lamellae) for source image distance SID₂. As thesource to image distance becomes closer to the anti-scatter grid 20, theenclosed (acute) angle α₁ between the extreme left slat in its firstposition 23 a and the base of the anti-scatter grid is smaller ascompared to the enclosed (acute) angle α₂ between the extreme slat inits second position 23 b and the base of the anti-scatter grid. Thus, atypical anti-scatter grid having fixed slats can only be optimized tohave optimum anti-scatter performance at a single source detectorseparation.

This application proposes that the slats (lamellae) of the grid areoriented such that they are parallel, or substantially parallel, to theincoming beams from the source of many different source to imagedistances across the lateral face of an X-Ray detector.

In systems with a variable source to image distance, the grid functionof a normal non-flexible anti-scatter grid is severely hampered atsource to image distance settings which differ from the nominal gridfocus. As a compromise, the grid parameters, most notably the gridratio, must be chosen to be relatively low. This enables theanti-scatter grid to function at the boundary of the allowed source toimage distance range this reduces the overall performance of the grid,and makes it less selective for discriminating primary (useful) fromsecondary (scatter) radiation as compared to a single fixed SID system.

FIG. 2 illustrates an example of an X-Ray imaging system according to athird aspect. In this case, the system is C-arm although thisapplication is addressed to any X-Ray imaging system with a variablesource to imager distance. The X-Ray imaging system comprises a C-arm 10supporting an X-Ray source 12 configured to emit X-rays in a beamthrough a region of interest 14 that may contain a patient in use. TheC-arm 10 further comprises an X-Ray detector 16 comprising an adaptiveanti-scatter grid (not shown in FIG. 2) according to a first aspect. TheC-arm 10 is physically supported from the ceiling via an azimuth joint11 and a tilt joint 13, enabling the positioning of the C-arm into avariety of positions around the region of interest 14. Furthermore, oneor both of the X-Ray source 12 and the X-Ray detector 16 may berepositionable between at least a first source to image distance SID₁and a second source to image distance SID₂. Preferably, therepositioning of the X-Ray source 12 relative to the X-Ray detector isalong a source to detector axis 18 that is orthogonal both to a planecontaining the X-Ray detector 16 and the X-Ray source 12 however, itwill be appreciated that the adaptive anti-scatter grid may also beapplied in arrangements where the X-Ray detector 16 and/or X-Ray source12 are slightly misaligned. The X-Ray imaging system also comprises acontroller 19 connected to the C-arm 10. The controller 19 is capable ofaccurately controlling the orientation of the C-arm 10 and the source toimage distance of the X-Ray source 12 and the X-Ray detector 16.Furthermore, the controller may generate control signals for theadaptive anti-scatter device based on the source to image distance ofthe X-Ray source and X-Ray detector 16.

Accordingly, if the slats (lamellae) of an anti-scatter device are notperfectly oriented towards the plane of the X-Ray source 12, a part ofthe direct radiation will intersect with the slats and be absorbed. Theamount of absorption depends on the slat depth and the misalignmentangle.

Accordingly, a solution to this problem is to provide a variable focusgrid in which the focal distance of the grid can be matched to theactual source to image distance across a range of source to imagedistances. For such grids, a higher aspect ratio can be chosen whichreduces the amount of scatter in the X-Ray image and improves imagequality for each source to image distance.

An insight of this application is that every slat (lamella) requires aspecific and different angulation based on its lateral separationdistance from the source to image axis (focal spot) of the X-Ray imagingsystem 10. Furthermore, the rate of change of each interior angle ofeach slat (lamella) with respect to the source to image distance will bedifferent. Accordingly, fine-grained control of the angulation of eachslat (lamella) is required as the source to image distance changes. Inother words, it is proposed to provide individually tuned lamellasteering. In principle, it is proposed to use 3D or 4D printing topartially or fully fill the interstitial spaces between slats (lamella)using smart materials, or a combination of smart materials and inertmaterials.

Smart materials respond to external stimuli by transforming their shapeand/or volume and changing their physical properties (for example,Young's modulus, stiffness, and resistance) in particular, smartmaterials that exhibit the shape-memory effect are able to recover theiroriginal shape following environmental transformation.

The recently developed techniques of 3D or 4D printing allow an accuratepositioning of smart materials at least partially within theinterstitial spaces of an anti-scatter grid to enable fine movements anddeformations to be made. For example, a printer such as the StratasysPolyjet™ enables small actuators to be provided inside, or partiallyinside, the interstitial spaces of an anti-scatter grid (voxel printtechnology). Using more advanced 3D or 4D printers, it is possible toprint or deposit the slats (lamellae) of the anti-scatter grid and theinterstitial actuators in a single 3D or 4D printer, for example.

FIG. 3a ) schematically illustrates the front face of an adaptiveanti-scatter device 20 according to a first aspect. In other words, anX-Ray source would be directed above the page looking down towards theanti-scatter grid. The adaptive anti-scatter device 20 may be placed inthe source-detector axis of an X-Ray imager. An example position 24 ofthe source-detector axis at a central portion of the adaptiveanti-scatter device 20 is illustrated, although it will be appreciatedthat the source-detector axis 22 can be offset from this position. Thuswhat is illustrated is a source orientable surface. The reverse (notvisible) is a detector orientable surface. The majority of the area ofthe adaptive anti-scatter device comprises a plurality of realignmentslats 24 in the y direction. Although illustrated as a rectangular gridwith regular spacing, the realignable slats (lamellae) may optionally bespaced irregularly, and oriented diagonally, for example.

The realignable slats 24 are fabricated from a material that functionsto interrupt scattered X-Ray radiation. In particular, the slats may beformed from lead, tungsten, bismuth, molybdenum, or alloys thereof.Thus, the gaps in between the slats comprise interstitial spaces 26. Thesurround of the adaptive anti-scatter device may optionally comprise asupport frame 28, although in some implementations the anti-scatter gridmay be supported directly in the chassis of an X-Ray detector and doesnot require an integral support frame 28.

FIG. 3b ) schematically illustrates an enlarged front view correspondingto the inset of the adaptive anti-scatter device illustrated in FIG. 3a).

Vertical slats 24 a-e run in the y direction which, in operation, istransverse to a source to detector X-Ray beam axis, and the plane of thevertical slats defines the lateral surface of the adaptive anti-scatterfilter that is directed towards an X-Ray source in operation. Thevertical slats 24 a-e are realignably attached to a base member of theadaptive anti-scatter device, for example using a strip of resilientpolymer that is attached to the slat and the base member. This enablesthe angle of the slat to change with respect to the source-detector axis22.

Highlighted box 26 a illustrates portion of an interstitial space.Interstitial space 26 a comprises a first set of one or more activelydeformable actuators (voxels) 28 a, 28 b. Although FIG. 3b ) illustratestwo actively deformable actuators 28 a, 28 b, it will be appreciatedthat the interstitial space 26 a could comprise 1, 2, 3, 4, 5, 6, 7, 8,9 or more actively deformable actuators. In other words, in a simplecase the entire interstitial space 26 a could comprise a singleactuator. This is repeated for all, or a significant percentage, of theinterstitial spaces of the adaptive anti-scatter device.

In the illustration, a portion of each of the actively deformableactuators 28 a, 28 b abut the vertical slats 24 a so that when theactively deformable actuators 28 a, 28 b expand, at least slat 24 a isrealigned (moved in a direction substantially transverse to the sourceto detector axis) proportionately to the expansion of the activelydeformable actuators 28 a, 28 b. Of course, the actively deformableactuators 28 a, 28 b may be designed only to produce expansion in atransverse direction away from the source-detector axis 22.Alternatively, the actively deformable actuators may be designed tocontract in a transverse direction towards the source-detector axis 22.Furthermore, the behavior of the actively deformable actuator may bedesigned to vary based upon its coordinate on the lateral surface of theadaptive anti-scatter device 20.

In the illustrated case, interstitial space 26 a also comprisesnon-essential inert elements 30 a, 30 b. These are not activelydeformable.

Optionally, the inert elements 30 a, 30 b may comprise an inert andresilient element (such as elastic, rubber, or silicon) capable ofchanging shape as the actively deformable actuators expand and contract.

Optionally, the inert elements 30 a, 30 b may comprise an inert and hardsubstance (such as a plastic polycarbonate) that does not change shapeas the actively deformable actuators expand and contract. The use ofinert materials in portions of the interstitial space that is notoccupied by an actively deformable actuator can enable the forcegenerated by the actively deformable actuators 28 a, 28 b to be directedtowards the slats in a controlled way.

For example, inert elements 30 a, 30 b are anchored to enable activelydeformable actuators 28 a, 28 b to exert a transverse expansive orcontractive force on realignable slat 24 a, but to isolate realignableslat 24 b from the transverse expansive or contractive force exerted byactively deformable actuators 28 a, 28 b.

It is not essential that the actively deformable actuators 28 a, 28 bdirectly about the slats 24 provided the force vector generated by theirexpansion or contraction can be transmitted to the slats 24. Forexample, the interstitial space 26 a could comprise an outerdonut-shaped ring of inert and resilient material, the inside of thedonut-shaped ring comprising an actively deformable material. In thiscase, the inward or outward expansion force would be transmitted throughthe inert and resilient material to the slats.

In either the case of the actively deformable material 28 a, 28 babutting the slats 24, and/or the inert material 30 a, 30 b abutting theslats 24 (where inert material is used), the actively deformablematerial 28 a, 28 b is provided so that it is partially, or fullyrecessed within the interstitial portions of the anti-scatter device 20.This enables the abutment (contact) of the actively deformable material28 a, 28 b (or the inert material 30 a, 30 b) onto the surface of theslats, so that the expansion or contraction force can be transmitted. Itis most preferable that the contact of the actively deformable material28 a, 28 b (or the inert material 30 a, 30 b) onto the side of the slatsoccurs with a substantially zero air-gap, to enable accurate realignmentof the slats as the actively deformable material 28 a, 28 b expands andcontracts.

FIG. 3c ) schematically illustrates a front view of an exemplary 2Dembodiment of the anti-scatter grid according to the first aspect.

The anti-scatter grid illustrated in FIGS. 3a ) and 3 b) comprises afirst plurality of parallel slats (lamellae) aligned in a firstdirection allowing the redirection of the grid along one axis. Theembodiment of FIG. 3c ) extends this concept by providing, in addition,a second plurality of slats 24 f, 24 g, 24 h, 24 i aligned transverse tothe first plurality of slats. The slats of the second plurality of slats24 f, 24 g, 24 h, 24 i are provided with cut-outs (not shown) atjunctions between the slats of the first and second pluralities ofslats. The function of the cutouts is to allow the slats of the firstplurality of slats to adjust their angle without colliding with theslats of the second plurality of slats. Furthermore, an additional setof 3D or 4D printed actuators abutting the slats of the second pluralityof slats are provided to function to manipulate the angle of the slatsof the second plurality of slats in the same manner as actuators 28 aand 28 b in relation to the first plurality of slats. Accordingly, anadjustable 2D anti-scatter grid may also be provided. FIG. 4a )schematically illustrates a side view of an exemplary anti-scatter gridaccording to the first aspect in a first (relaxed) configuration. Inthis figure, a side view of slats 24 a, 24 b, is given. Slat 24 ₀ isperpendicular to the base member 21. Slat 24 a initially encloses anangle of ϑ_(a1). Slat 24 b initially encloses an angle of ϑ_(b1). Thefirst actively deformable member 26 a comprises actively deformableactuator 28 a abutting 24 a. Furthermore, the first actively deformablemember 26 a comprises a non-essential inert, or less deformable member30 a. This configuration is appropriate for the source to image distanceSID₁ (a first alignment) enabling good separation of scatteredX-radiation.

FIG. 4b ) schematically illustrates a side view of an exemplaryanti-scatter grid according to the first aspect in a second (contracted)configuration. The source to image distance SID₂ has been moved closerto the adaptive anti-scatter grid, necessitating a change in angulationof the slats 24 a, and 24 b. Accordingly, a control signal (not shown)causes the first actively deformable member 26 a to contract, thusreducing the enclosed angles of the slats ϑ_(b1) and ϑ_(b2) to angles (asecond alignment) appropriate for good X-Ray scatter rejection at thesource position SID₂.

Although not illustrated, a cover element that is translucent X-rays maybe provided to cover at least one side of the adaptive anti-scatterdevice to provide mechanical protection, for example. Slats of theanti-scatter grid may, in this case, be coupled to the cover elementusing a resilient material that enables re-angulation of the slats.

Optionally, the anti-scatter device further comprises a second activelydeformable member comprising a third set of one or more activelydeformable actuators configured to change the alignment of acorresponding slat of the anti-scatter filter in relation to thesource-detector axis. One or more actively deformable actuators of thethird set of one or more actively deformable actuators is formed withinthe interstitial portions of the anti-scatter filter and in contact withat least one corresponding slat of the plurality of slats, so that adeformation of an actively deformable actuator of the third set of oneor more actively deformable actuators causes a corresponding change tothe alignment of the at least one corresponding slat relative to thesource-detector axis.

The second actively deformable member is provided in lateral alignmentwith the first actively deformable member along the source detectoraxis. In other words, an adaptive anti-scatter device according to thisembodiment comprises a layered structure of first and second activelydeformable members. Of course, third, fourth, fifth, and more layers ofactively deformable members may be provided. The additional layers ofactively deformable members optionally actuated using a unified controlsignal, to ensure that they expand in proportion to each other (to avoidbending or curling the slats). By providing additional layers ofactively deformable members abutting the slats at the depth of therespective additional layers of actively deformable members, a morerigid attachment of the slats is provided.

Accordingly, a second actively deformable member positioned in theanti-scatter device further from a source position than the firstactively deformable member may comprise a smaller lateral spatialdensity of actively deformable actuators compared to the first activelydeformable member.

Accordingly, a third actively deformable member positioned in theanti-scatter device further from a source position than the secondactively deformable member may comprise a smaller lateral spatialdensity of actively deformable actuators compared to the second activelydeformable member.

Optionally, a member positioned in the anti-scatter device furtherstrong source position compared to other actively deformable members maybe comprised entirely of inert material to function as a slat former.

By varying the lateral spatial density of actively deformable actuatorsabutting the anti-scatter grid in each layer of actively deformablemembers in the adaptive anti-scatter device, account is taken that theslats will each need to be moved at their greatest lateral displacementAA, AB at the lateral face of the adaptive anti-scatter device closestto the source. For a layer of actively deformable members at the layerof the anti-scatter device furthest from the source direction, a smallor zero lateral displacement of the slat is required. For an activelydeformable member placed substantially in the middle of the depth of theanti-scatter device, a middling displacement of the slats in between theextremes of slat displacement required at the outer faces of theanti-scatter device is required. Accordingly, the lateral spatialdensity of actively deformable actuators is optionally greater on afirst actively deformable member of an adaptive anti-scatter device thatis closest to an X-Ray source, and the lateral spatial density ofactively deformable actuators is optionally smaller on a third or secondactively deformable member that are further away from the X-Ray source.

FIG. 5a ) and b) schematically illustrate side views of an adaptiveanti-scatter device 30 in a first and a second state. The illustratedadaptive anti-scatter device 30 is similar to that illustrated in FIGS.4a ) and b), and comprises three layers of actively deformable members:an upper layer 32 closest to a variable X-Ray source position S₁, S₂, amiddle layer 34, and a bottom layer 36 furthest from a variable X-Raysource position S₁, S₂. The three layers of actively deformable membersabout the slat 39 and 40. A similar set of three layers of activelydeformable members would be provided between slats 40 and 42. FIG. 5a )illustrates the configuration of the actively deformable members in anuncontracted position 32 _(A), 34 _(A), 36 _(A). FIG. 5b ) illustratesthe configuration of the actively deformable members in a contractedposition 32 _(B), 34 _(B), 36 _(B). As shown, the first activelydeformable member 32 closer to the X-Ray source must expand and contractwith a greater displacement as compared to the third actively deformablemember 36.

Notably, the actively deformable actuator applied in the first, second,and/or third actively deformable members may act to contract or toexpand, dependent on the material or design of the actively deformableactuator.

Although FIG. 5 illustrates an adaptive anti-scatter device comprisingthree actively deformable members at different times, it is not excludedthat an adaptive anti-scatter device comprising two actively deformablemembers at different layers of the adaptive anti-scatter device isprovided.

The ratio between active and less active actuators determines what themaximum contraction (or expansion) force and distance is between twoslats (lamellae) at a certain location of the filter. The difference incontraction between the top side and the bottom side (source facing anddetector facing sides) determines the orientation of the slats.Additionally, progressively more off-axis slats may need to be angled ata greater rate than the slats closer to the source to detector. Thus, agreater number of active elements, or an active element capable of agreater displacement change, may be required closer towards theextremities of the filter as compared with the source to detector axis.Of course, smaller 3D printed actuators enable more precise steering ofthe slats. Typically, an anti-scatter filter (grid) may have 44 linesper centimeter, and an actuator size of around 25 to 30 microns,allowing approximately 10 actuators to fit in the interstitial space ofa typical grid. The number of actuators that may be fitted into theinterstitial space of a typical grid is variable based on the type ofgrid, and the type of 3D or 4D printing used to construct the actuators.

Optionally, the first actively deformable member further comprises asecond set of one or more actively deformable actuators disposed in asecond region of the first actively deformable member. The first regionis laterally closer to the source-detector axis than the second region.The second region of the first actively deformable member comprises agreater spatial density of actively deformable actuators than the firstregion.

FIG. 6 schematically illustrates a front view of a further exemplaryanti-scatter filter 44 comprising a varying lateral spatial density ofactive actuators. The number of actively deformable actuators has beenreduced in this representation to enable clearer understanding. Theanti-scatter filter 44 comprises a first plurality of activelydeformable actuators that will be referenced along a first lateraldirection using the coordinates A-E and along a second lateral directionusing the coordinates 1-5. Thus, the source-detector center axis 46 islocated in C3. The actively deformable actuators are shown grouped intosquare groups of four with inert (or less deformable) portions.

Optionally, member C3 containing the source-detector axis 46 does notcomprise an actively deformable actuator because it is located on thesource-detector center axis 46. It may be comprised of an air gap, or aninert resilient or non-resilient material, for example. Alternativelyhowever, member C3 may comprise an actively deformable actuator. Theline C1, C2, C3, C4, C5 likewise does not comprise deformable actuators.

In FIG. 6, the members either side of the source-detector axis 46 incolumns B and D comprise a first region of actively deformable actuators(filled squares) forming substantially one half of the space inside theinterstitial region between slats separating the actively deformableactuators. The remainder of the space inside the interstitial regions ofthese actuators may optionally be empty (comprised of air), or comprisedof a resilient or non-resilient inert material (such as plastic orsilicone, for example).

Moving laterally further away from source-detector axis 46, the lines ofmembers in columns A and E comprise a second region of activelydeformable actuators (filled squares) occupying substantially all ofspace inside each interstitial region between slats separating theactively deformable actuators in other words, the second region ofactively deformable actuators further from the source-detector axis hasa greater lateral spatial density of actively deformable actuatorscompared to the first region of actively deformable actuators that areclose to the source-detector axis 46. Accordingly, in this embodimentthe density of the actively deformable actuators increases as thelateral distance across the grid from the source to detector axisincreases.

In operation (and assuming that the actively deformable actuatorsillustrated all provide an equal displacement), actively deformableactuators of columns A and E tend to deflect the slats of the adaptiveanti-scatter filter 44 in the X and Y directions to a greater extentcompared to actively deformable actuators of the first region.Accordingly, scattered X-Ray radiation can be effectively filtered atdifferent lateral regions of an X-Ray detector. It is not essential thatthe first and second regions of actively deformable actuators containdifferent integer numbers of actively deformable actuators. For example,each interstitial space in actively deformable members A-E, 1-5 maycomprise one actively deformable actuator configured to expand orcontract by the same amount upon the application of the driving signal.Optionally, each interstitial space in actively deformable members A-E,1-5 may comprise one actively deformable actuator configured to expandor contract by a different amount upon the application of the drivingsignal depending on its location either in the first or the secondregion. This may be achieved by, for example, depositing a larger orsmaller deposit of electro-active polymer at the relevant actuatorlocation, for example.

Optionally, the actuators of the first and/or second actively deformablemember are controllable with a unified control signal, or the actuatorsof the first and/or second actively deformable member are divided intoindividually addressable actuator regions.

FIG. 6 illustrates a 1D anti-scatter grid with grids in the y directiononly, having a variation in density of the deformable actuators withlateral distance from the source to detector axis in the x direction.

However, an adaptive X-ray anti scatter grid may be provided havingslats in the X and Y direction. In this case, a 2D variation in densityof the deformable actuators with lateral distance from the source todetector axis can be provided.

Furthermore, in a 1D anti-scatter grid with grids in the y directiononly, a 2D variation in density of the deformable actuators with lateraldistance from the source to detector axis can be provided in order toprovide a non-equal deflection of the slats in x direction of a 1D grid.FIG. 7 schematically illustrates a front view of a further exemplaryanti-scatter filter of FIG. 6 additionally comprising a control signalarrangement 48 _(A), 48 _(B). The control signal arrangement 48 _(A), 48_(B) enables a signal controlling the deformation of actively deformableactuators to be conveyed from a control means to a plurality of activelydeformable actuators. As will be appreciated, the control signalarrangement 48 _(A), 48 _(B) depends on the type of actively deformableactuator used. In the case of electro-active polymers or thermallyactive alloys, the control signal may, for example, be a digitalelectronic signal or an analogue electronic signal brought intoelectrical contact with the electro-active polymer or a heater near thethermally active alloy. In the case that the actively deformableactuator is a microfluidic inflatable or deflatable element, the controlsignal may, for example, be a microfluidic channel capable of carrying agas or a non-compressible liquid. Furthermore, the control signalarrangement 48 _(A), 48 _(B) can enable the unified addressing of allactively deformable actuators of the entire adaptive anti-scatter device(requiring a less complicated control circuit). Alternatively, thecontrol signal arrangement 48 _(A), 48 _(B) can enable the specificaddressing of individual actively deformable actuators, sub-groups ofactively deformable actuators, or specific layers of actively deformableactuators.

FIGS. 8a ) to c) schematically illustrate a deformable auxeticcontraction cell in various degrees of contraction. Accordingly, anactively deformable actuator can be provided as an auxetic contraction(or expansion) cell. Alternatively or in combination, an activelydeformable actuator is provided as a combination of a deformable auxeticcontraction cell with a portion of electro-active polymer or the othertechniques discussed previously.

According to a second aspect, there is provided an X-ray detectorassembly comprising:

-   -   an X-ray detector, and    -   at least one adaptive anti-scatter device according to the first        aspect or its embodiments.

For example, the X-Ray detector assembly comprises a flat-panel digitalX-Ray detector is known to a person skilled in the art, with the atleast one adaptive anti-scatter device mounted onto the source-facingside of the flat-panel digital X-Ray detector.

According to a third aspect, there is provided an X-ray imaging system 8having a variable source-imaging distance SID₁, SID₂ comprising:

-   -   an X-ray source 12 configured to emit a beam of X-ray radiation        directed towards a patient imaging area 14 of the X-ray imaging        system along a source-detector axis;    -   an X-ray detector assembly 16 according to the second aspect        configured to detect X-ray radiation emitted from the X-ray        source; and    -   a controller 19 configured to provide a control signal to the        first actively deformable member of the adaptive anti-scatter        device of the X-ray detector.

The X-ray source 12 and/or the X-ray detector 16 are configurable sothat they can be separated by at least a first SID₁ and a second SID₂different source detector distance.

The controller 19 is configured to monitor the source detector distanceof the X-ray source and X-ray detector, and to generate a control signalfor the first actively deformable member, to set the first activelydeformable member using the control signal, and to obtain X-ray imagingdata from the X-ray detector 16 with the first actively deformablemember configured at an appropriate alignment for the source detectordistance of the X-ray source and X-ray detector.

Optionally, the controller 19 is configured to obtain source detectorseparation information from the X-Ray imaging system control software,and/or from sensors inside the X-Ray imaging system motion drivecircuitry.

The controller 19 is configured to output control signals to theadaptive anti-scatter device configured to adjust actively deformableactuators so that slats in the anti-scatter device are removed from afirst alignment to a second alignment relative to the source-detectoraxis, to enable an appropriate slat alignment to provide for a givensource detector separation distance. For example, the output controlsignals may be generated by a lookup table, a mathematical function, orby an online feedback loop that monitors the quality of the receivedimage and makes minor adjustments to the alignment of the slats toreduce scatter.

According to a fourth aspect, there is provided a method formanufacturing an adaptive anti-scatter device comprising:

-   -   a) providing an anti-scatter filter having a source orientable        surface and a detector orientable surface, wherein the        anti-scatter filter comprises a plurality of realignable slats        for absorbing incident X-rays, wherein the realignable slats are        separated by a plurality of interstitial portions; and    -   b) providing a first actively deformable member comprising a        first set of one or more actively deformable actuators disposed        across a first region of the first actively deformable member,        wherein one or more of the first set of one or more actively        deformable actuators are configured to change the alignment of a        corresponding slat of the anti-scatter filter in relation to the        source-detector axis. At least a portion of one or more of the        first set of one or more actively deformable actuators is        partially or fully recessed within the interstitial portions of        the anti-scatter filter. One or more of the first set of        actively deformable actuators is in contact with at least one        realignable slat of the plurality of slats, so that a        deformation of the at least one of the first set of one or more        actively deformable actuators causes a corresponding change to        the alignment of the at least one corresponding slat from a        first alignment to a second alignment relative to the        source-detector axis.

The method of manufacturing an adaptive anti-scatter-device using 3Dprinting may comprise providing the first actively deformable member asa sub-component to be integrated with a previously manufacturedanti-scatter grid.

For example, the X-Ray absorbing slats could be provided as metal sheets(such as molybdenum or tungsten) fixed on a first side in a plasticcarrier having fixed pitch, and on the source-facing side with firstactively deformable members as discussed previously. Alternatively, a 3Dprinter may be used simultaneously to print the grid and the activelydeformable members.

According to a fifth aspect, there is provided a computer programelement comprising instructions for the operation of a 3D or 4D printerwhich, when addressed to a 3D or 4D printer, cause the 3D or 4D printerto follow the method of the fourth aspect. For example, the computerprogram element may comprise instructions in common 3D or 4D printerfile formats such as STL, OBJ, FBX, COLLADA, 3DS, IGES, STEP, andVRML/X3D. These files may be compiled using 3D or 4D printer designsoftware is known in the art.

According to a sixth aspect, there is provided a computer readablemedium comprising instructions for the operation of a 3D or 4D printerof the fifth aspect.

A computer program element might therefore be stored on a computer unit,which might also be an embodiment of the present invention. Thiscomputing unit may be adapted to perform or induce performance of thesteps of the method described above. The computing unit can be adaptedto operate automatically and/or to execute orders of a user. A computerprogram may be loaded into a working memory of a data processor. Thedata processor may thus be equipped to carry out the method of theinvention.

This exemplary embodiment of the invention covers both a computerprogram that has the invention installed from the beginning, and acomputer program that by means of an update turns an existing programinto a program that uses the invention.

The 3D or 4D printer data can be provided to a 3D or 4D printer over alocal area network, or save on physical media such as a digitalversatile disc, tape drive, or USB stick. The 3D or 4D printer data maybe stored and/or distributed on a suitable medium, such as opticalstorage media, or a solid-state medium supplied together with, or aspart of other hardware, but may also be distributed in other forms suchas via the Internet or other wired or wireless telecommunicationsystems. However, the computer program may also be presented over anetwork like the World Wide Web, and can also be downloaded into theworking memory of a data processor from such a network.

It should be noted that aspects and embodiments of the invention havebeen described with reference to different subject matter. Inparticular, some embodiments are described with reference to method-typeclaims, whereas other embodiments are described with reference todevice-type claims. A person skilled in the art will, however, gatherfrom the above and following description, that, unless otherwisenotified, in addition to any combination of features belonging to onetype of subject-matter, also any combination between features related todifferent subject-matter is considered to be disclosed with thisapplication. All features discussed herein can be combined providingsynergetic effects that are more than simply a summation of thefeatures. While the invention has been illustrated and described indetail in the drawings and foregoing description, such illustration anddescription are to be considered illustrative or exemplary, and notrestrictive. The invention is not limited to the disclosed embodiments.Other variations to the disclosed embodiments can be understood andeffected by those skilled in the art practicing the claimed inventionfrom a study of the drawings. The disclosure, and the dependent claims.

In the claims, the word “comprising” does not exclude other elements orsteps and the indefinite article “a” or “an” does not exclude aplurality. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage. Any reference signs in the claimsshould not be construed as limiting the scope.

1. An adaptive X-ray anti-scatter device for placement in asource-detector axis of an X-ray imager comprising: an anti-scatterfilter having a source orientable surface and a detector orientablesurface, wherein the anti-scatter filter comprises a plurality ofrealignable slats for absorbing incident X-rays, wherein the slats areseparated by a plurality of interstitial portions; and a first activelydeformable member comprising a first set of one or more activelydeformable actuators disposed across a first region of the firstactively deformable member, wherein at least a portion of the first setof one or more actively deformable actuators is partially or fullyrecessed within the interstitial portions of the anti-scatter filter,and wherein at least one actuator of the first set of one or moreactively deformable actuators is in contact with at least onerealignable slat of the plurality of slats, the at least one actuatorbeing configured to change the alignment of the corresponding at leastone realignable slat in relation to the source-detector axis.
 2. Theadaptive anti-scatter device according to claim 1, further comprising: acover element arranged to cover at least one side of the adaptiveanti-scatter device, wherein the slats of the anti-scatter filter arecoupled to the cover element.
 3. The adaptive anti-scatter deviceaccording to claim 1, wherein the lateral spatial density of activelydeformable actuators of the first actively deformable member varies as afunction of the lateral location on the first actively deformablemember.
 4. The adaptive anti-scatter device according to claim 1,wherein the first actively deformable member further comprises: a secondset of one or more actively deformable actuators disposed in a secondregion of the first actively deformable member; wherein the first regionis laterally closer to the source-detector axis than the second region;wherein the second region of the first actively deformable membercomprises a greater spatial density of actively deformable actuatorsthan the first region.
 5. The adaptive anti-scatter device according toclaim 1, further comprising: a second actively deformable membercomprising a third set of one or more of actively deformable actuatorsconfigured to change the alignment of a corresponding slat of theanti-scatter filter in relation to the source-detector axis, wherein oneor more actuators of the third set is formed within the interstitialportions of the anti-scatter filter and in contact with at least onecorresponding slat of the plurality of slats, so that a deformation ofan actively deformable actuator of the third set of one or more activelydeformable actuators causes a corresponding change to the alignment ofthe at least one corresponding slat relative to the source-detectoraxis.
 6. The adaptive anti-scatter device according claim 5, wherein thesecond actively deformable member is located closer to thesource-orientable face than the first actively deformable member; andwherein the lateral spatial density of actively deformable actuators ofthe second actively deformable member is greater than the lateralspatial density of the actively deformable actuators of the firstactively deformable member at corresponding lateral positions of thefirst and second deformable members.
 7. The adaptive anti-scatter deviceaccording claim 1, wherein the interstitial spaces of the anti-scatterfilter comprise actuators of the first and/or second actively deformablemember, wherein one or more of the interstitial spaces comprise a firstset of one or more actively deformable actuators, and a second pluralityof non-deformable actuators, or actuators that are less deformable thanthe actuators in the first set of one or more actively deformableactuators.
 8. The adaptive anti-scatter device according to claim 1,wherein the actuators of the first and/or second actively deformablemember are controllable with a unified control signal, or the actuatorsof the first and/or second actively deformable member are divided intoindividually addressable actuator regions.
 9. The adaptive anti-scatterdevice according to claim 1, wherein at least one of the first, second,and/or third pluralities of actively deformable actuators compriseactively deformable actuators of an electro-active or thermally-activepolymer or metal alloy.
 10. An X-ray detector comprising: at least oneanti-scatter device according to claim
 1. 11. An X-ray imaging systemhaving a variable source-imaging distance comprising: an X-ray sourceconfigured to emit a beam of X-ray radiation directed towards a patientimaging area of the X-ray imaging system along a source-detector axis;an X-ray detector according to claim 10 configured to detect X-rayradiation emitted from the X-ray source; and a controller configured toprovide a control signal to the first actively deformable member of theanti-scatter device of the X-ray detector; wherein the X-ray sourceand/or the X-ray detector are configurable so that they can be separatedby a first and a second different source detector distances; and whereinthe controller is configured to monitor the source detector distance ofthe X-ray source and X-ray detector, to generate a control signal forthe first actively deformable member, to set the first activelydeformable member using the control signal, and to obtain X-ray imagingdata from the X-ray detector with the first actively deformable memberconfigured appropriately for the source detector distance of the X-raysource and X-ray detector.
 12. A method for manufacturing an adaptiveanti-scatter device comprising: a) providing an anti-scatter filterhaving a source orientable surface and a detector orientable surface,wherein the anti-scatter filter comprises a plurality of realignableslats for absorbing incident X-rays, wherein the realignable slats areseparated by a plurality of interstitial portions; b) providing a firstactively deformable member comprising a first set of one or moreactively deformable actuators disposed across a first region of thefirst actively deformable member, including: providing at least aportion of the first set of one or more actively deformable actuatorswithin the interstitial portions of the anti-scatter filter in apartially or fully recessed manner, and contacting at least one actuatorof the first set of one or more actively deformable actuators with atleast one realignable slat of the plurality of slats such that adeformation of the at least one actuator causes a change of thealignment of the corresponding slat in relation to the source-detectoraxis.
 13. The method for manufacturing an adaptive anti-scatter deviceaccording to claim 12, wherein either or both of a) and/or b) areperformed using a 3D or a 4D printer.
 14. A computer program elementcomprising instructions for the operation of a 3D or 4D printer which,when addressed to a 3D or 4D printer, cause the 3D or 4D printer tofollow the method according to claim
 13. 15. A computer readable mediumcomprising instructions for the operation of a 3D or 4D printer definedin claim 14.